This shared instrument proposal is for purchase of a dedicated small-animal SPECT system with multi-pinhole imaging capability. The NIH-funded research projects that require this system are aimed at developing new molecular imaging agents and the use of standard radiotracers to investigate fundamental biological processes and to assess the impact of therapeutic interventions. This proposal describes nine major projects in which SPECT studies of small animals will be used to assess fundamental questions in cancer biology and bone-fracture healing. The system will be located in the Center for Small Animal Imaging (CSAI) alongside systems representing the other major in vivo imaging modalities (ultrasound, bioluminescence/fluorescence, microCT, microPET, MRI and MRS). The CSAI functions as a Core Facility for the university and operates as part of the Vanderbilt University Institute of Imaging Science. The SPECT system will be supported by an experienced group of imaging scientists and a highly qualified support staff. It will be a key resource for postdoctoral trainees supported by our institutional training program in cancer imaging. Vanderbilt University is a member of both the Tennessee Mouse Genome Consortium and the Mouse Models of Human Cancer Consortium. This extensive research in mouse models of human disease will benefit from the availability of this new tool that will enable investigators to probe disease mechanisms and characteristics, to study disease progression, and to assess both novel diagnostics and therapeutics. The inherently translational nature of SPECT radiotracers means that the knowledge and tools developed through research with this system will have a pathway to the clinic and, therefore, will help to enhance research from bench to bedside. [unreadable] [unreadable] [unreadable]